Paul prays that the growth of love in knowledge and discernment may result in Christians better approving what is excellent—that which really matters, that which is essential. Then the believers will be pure and blameless for the day of Christ.
Pure meaning inwardly pure. Blameless: that there is nothing to fault about them.
10 pour le discernement des choses les meilleures, afin que vous soyez purs et irréprochables pour le jour de Christ,